In arc welding with flux-cored electrodes, it is desirable to keep the length of the arc as short as possible. Short arc length minimizes the contamination of the weld metal by oxygen, nitrogen, and hydrogen from the atmosphere or the shielding gas and therefore reduces the need for killing agents, such as magnesium, aluminum, silicon, titanium, and/or zirconium, in the weld. Since both the contaminants and the killing agents can be detrimental to the physical properties of the weld deposit, minimizing the arc length is a way to facilitate improvements in those properties.
However, shortening the arc length, whether by simply reducing the arc voltage or by advanced waveform control techniques, can result in a cold weld puddle, which in turn can lead to poor weld bead shapes (for example, convex or “ropey” shapes) and defects such as lack of fusion and slag entrapment. Accordingly, there is a need for a technique in which arc length can be shortened, while avoiding the problems such as faulty weld bead shape otherwise resulting from short arc length. Additionally, it would be desirable to provide welding consumables, such as electrodes, that are specifically tailored to provide, at a given welding power level or a reduced level, a weld puddle with a predetermined set of characteristics, such as a desired shape or profile.
The rate of metal deposition during a welding process affects the properties of the resulting weld and overall productivity. However, increased gains in productivity from higher deposition rates can be offset by increased energy requirements associated with high energy arc welding processes. Accordingly, it would be beneficial to provide a strategy by which increased deposition rates could be achieved without the attendant increased welding energy demands.
Weld metal properties are influenced at least in part by the cooling rate of the welded assembly, which in turn depends on the temperature of the assembly that is reached during welding. As is known, the weld temperature can be adjusted by adjusting the power input to an arc welder. However, it is often desired to use reduced power levels in view of energy costs. Accordingly, it would be desirable to provide a technique for achieving a particular welding temperature without resorting to increasing welding power levels.
Moreover, achieving particular weld metal compositions is a constant goal in welding technology. Although prior artisans have made considerable advances in such endeavors, producing desired weld metal compositions has primarily been achieved by selecting particular welding consumables, and not by consideration of the power requirements of the welder. As previously noted, increasing energy costs are always a concern. Therefore, it would be beneficial if certain weld metal compositions could be produced while also reducing power demands of the welder. Accordingly, there is a need for a strategy in which particular weld metal compositions can be produced in conjunction with reducing overall power requirements for a welding unit.
All of the noted objectives relate to achieving particular weld characteristics or properties and preferably, without increasing the electrical power to a welding unit.